/*
    Sha1.cpp - source code of
    ============
    SHA-1 in C++
    ============
    100% Public Domain.
    Original C Code
        -- Steve Reid <steve@edmweb.com>
    Small changes to fit into bglibs
        -- Bruce Guenter <bruce@untroubled.org>
    Translation to simpler C++ Code
        -- Volker Grabsch <vog@notjusthosting.com>
    Safety fixes
        -- Eugene Hopkinson <slowriot at voxelstorm dot com>

--------------------------------------------------------------------
|    Sourced from: https://github.com/vog/sha1                     |
|    Altered for inclusion within frnetlib.                        |
--------------------------------------------------------------------
*/

#include "frnetlib/Sha1.h"
#include <sstream>
#include <iomanip>
#include <fstream>


namespace fr
{
    static const size_t BLOCK_INTS = 16;  /* number of 32bit integers per Sha1 block */
    static const size_t BLOCK_BYTES = BLOCK_INTS * 4;


    static void reset(uint32_t digest[], std::string &buffer, uint64_t &transforms)
    {
        /* Sha1 initialization constants */
        digest[0] = 0x67452301;
        digest[1] = 0xefcdab89;
        digest[2] = 0x98badcfe;
        digest[3] = 0x10325476;
        digest[4] = 0xc3d2e1f0;

        /* Reset counters */
        buffer = "";
        transforms = 0;
    }


    static uint32_t rol(const uint32_t value, const size_t bits)
    {
        return (value << bits) | (value >> (32 - bits));
    }


    static uint32_t blk(const uint32_t block[BLOCK_INTS], const size_t i)
    {
        return rol(block[(i + 13) & 15] ^ block[(i + 8) & 15] ^ block[(i + 2) & 15] ^ block[i], 1);
    }


/*
 * (R0+R1), R2, R3, R4 are the different operations used in Sha1
 */

    static void
    R0(const uint32_t block[BLOCK_INTS], const uint32_t v, uint32_t &w, const uint32_t x, const uint32_t y, uint32_t &z,
       const size_t i)
    {
        z += ((w & (x ^ y)) ^ y) + block[i] + 0x5a827999 + rol(v, 5);
        w = rol(w, 30);
    }


    static void
    R1(uint32_t block[BLOCK_INTS], const uint32_t v, uint32_t &w, const uint32_t x, const uint32_t y, uint32_t &z,
       const size_t i)
    {
        block[i] = blk(block, i);
        z += ((w & (x ^ y)) ^ y) + block[i] + 0x5a827999 + rol(v, 5);
        w = rol(w, 30);
    }


    static void
    R2(uint32_t block[BLOCK_INTS], const uint32_t v, uint32_t &w, const uint32_t x, const uint32_t y, uint32_t &z,
       const size_t i)
    {
        block[i] = blk(block, i);
        z += (w ^ x ^ y) + block[i] + 0x6ed9eba1 + rol(v, 5);
        w = rol(w, 30);
    }


    static void
    R3(uint32_t block[BLOCK_INTS], const uint32_t v, uint32_t &w, const uint32_t x, const uint32_t y, uint32_t &z,
       const size_t i)
    {
        block[i] = blk(block, i);
        z += (((w | x) & y) | (w & x)) + block[i] + 0x8f1bbcdc + rol(v, 5);
        w = rol(w, 30);
    }


    static void
    R4(uint32_t block[BLOCK_INTS], const uint32_t v, uint32_t &w, const uint32_t x, const uint32_t y, uint32_t &z,
       const size_t i)
    {
        block[i] = blk(block, i);
        z += (w ^ x ^ y) + block[i] + 0xca62c1d6 + rol(v, 5);
        w = rol(w, 30);
    }


/*
 * Hash a single 512-bit block. This is the core of the algorithm.
 */

    static void transform(uint32_t digest[], uint32_t block[BLOCK_INTS], uint64_t &transforms)
    {
        /* Copy digest[] to working vars */
        uint32_t a = digest[0];
        uint32_t b = digest[1];
        uint32_t c = digest[2];
        uint32_t d = digest[3];
        uint32_t e = digest[4];

        /* 4 rounds of 20 operations each. Loop unrolled. */
        R0(block, a, b, c, d, e, 0);
        R0(block, e, a, b, c, d, 1);
        R0(block, d, e, a, b, c, 2);
        R0(block, c, d, e, a, b, 3);
        R0(block, b, c, d, e, a, 4);
        R0(block, a, b, c, d, e, 5);
        R0(block, e, a, b, c, d, 6);
        R0(block, d, e, a, b, c, 7);
        R0(block, c, d, e, a, b, 8);
        R0(block, b, c, d, e, a, 9);
        R0(block, a, b, c, d, e, 10);
        R0(block, e, a, b, c, d, 11);
        R0(block, d, e, a, b, c, 12);
        R0(block, c, d, e, a, b, 13);
        R0(block, b, c, d, e, a, 14);
        R0(block, a, b, c, d, e, 15);
        R1(block, e, a, b, c, d, 0);
        R1(block, d, e, a, b, c, 1);
        R1(block, c, d, e, a, b, 2);
        R1(block, b, c, d, e, a, 3);
        R2(block, a, b, c, d, e, 4);
        R2(block, e, a, b, c, d, 5);
        R2(block, d, e, a, b, c, 6);
        R2(block, c, d, e, a, b, 7);
        R2(block, b, c, d, e, a, 8);
        R2(block, a, b, c, d, e, 9);
        R2(block, e, a, b, c, d, 10);
        R2(block, d, e, a, b, c, 11);
        R2(block, c, d, e, a, b, 12);
        R2(block, b, c, d, e, a, 13);
        R2(block, a, b, c, d, e, 14);
        R2(block, e, a, b, c, d, 15);
        R2(block, d, e, a, b, c, 0);
        R2(block, c, d, e, a, b, 1);
        R2(block, b, c, d, e, a, 2);
        R2(block, a, b, c, d, e, 3);
        R2(block, e, a, b, c, d, 4);
        R2(block, d, e, a, b, c, 5);
        R2(block, c, d, e, a, b, 6);
        R2(block, b, c, d, e, a, 7);
        R3(block, a, b, c, d, e, 8);
        R3(block, e, a, b, c, d, 9);
        R3(block, d, e, a, b, c, 10);
        R3(block, c, d, e, a, b, 11);
        R3(block, b, c, d, e, a, 12);
        R3(block, a, b, c, d, e, 13);
        R3(block, e, a, b, c, d, 14);
        R3(block, d, e, a, b, c, 15);
        R3(block, c, d, e, a, b, 0);
        R3(block, b, c, d, e, a, 1);
        R3(block, a, b, c, d, e, 2);
        R3(block, e, a, b, c, d, 3);
        R3(block, d, e, a, b, c, 4);
        R3(block, c, d, e, a, b, 5);
        R3(block, b, c, d, e, a, 6);
        R3(block, a, b, c, d, e, 7);
        R3(block, e, a, b, c, d, 8);
        R3(block, d, e, a, b, c, 9);
        R3(block, c, d, e, a, b, 10);
        R3(block, b, c, d, e, a, 11);
        R4(block, a, b, c, d, e, 12);
        R4(block, e, a, b, c, d, 13);
        R4(block, d, e, a, b, c, 14);
        R4(block, c, d, e, a, b, 15);
        R4(block, b, c, d, e, a, 0);
        R4(block, a, b, c, d, e, 1);
        R4(block, e, a, b, c, d, 2);
        R4(block, d, e, a, b, c, 3);
        R4(block, c, d, e, a, b, 4);
        R4(block, b, c, d, e, a, 5);
        R4(block, a, b, c, d, e, 6);
        R4(block, e, a, b, c, d, 7);
        R4(block, d, e, a, b, c, 8);
        R4(block, c, d, e, a, b, 9);
        R4(block, b, c, d, e, a, 10);
        R4(block, a, b, c, d, e, 11);
        R4(block, e, a, b, c, d, 12);
        R4(block, d, e, a, b, c, 13);
        R4(block, c, d, e, a, b, 14);
        R4(block, b, c, d, e, a, 15);

        /* Add the working vars back into digest[] */
        digest[0] += a;
        digest[1] += b;
        digest[2] += c;
        digest[3] += d;
        digest[4] += e;

        /* Count the number of transformations */
        transforms++;
    }


    static void buffer_to_block(const std::string &buffer, uint32_t block[BLOCK_INTS])
    {
        /* Convert the std::string (byte buffer) to a uint32_t array (MSB) */
        for(size_t i = 0; i < BLOCK_INTS; i++)
        {
            block[i] = (buffer[4 * i + 3] & 0xff)
                       | (buffer[4 * i + 2] & 0xff) << 8
                       | (buffer[4 * i + 1] & 0xff) << 16
                       | (buffer[4 * i + 0] & 0xff) << 24;
        }
    }


    Sha1::Sha1()
    {
        reset(digest, buffer, transforms);
    }


    void Sha1::update(const std::string &s)
    {
        std::istringstream is(s);
        update(is);
    }


    void Sha1::update(std::istream &is)
    {
        while(true)
        {
            char sbuf[BLOCK_BYTES];
            is.read(sbuf, BLOCK_BYTES - buffer.size());
            buffer.append(sbuf, is.gcount());
            if(buffer.size() != BLOCK_BYTES)
            {
                return;
            }
            uint32_t block[BLOCK_INTS];
            buffer_to_block(buffer, block);
            transform(digest, block, transforms);
            buffer.clear();
        }
    }


/*
 * Add padding and finish up
 */

    void Sha1::final()
    {
        /* Total number of hashed bits */
        uint64_t total_bits = (transforms * BLOCK_BYTES + buffer.size()) * 8;

        /* Padding */
        buffer += static_cast<char>(0x80);
        size_t orig_size = buffer.size();
        while(buffer.size() < BLOCK_BYTES)
        {
            buffer += static_cast<char>(0x00);
        }

        uint32_t block[BLOCK_INTS];
        buffer_to_block(buffer, block);

        if(orig_size > BLOCK_BYTES - 8)
        {
            transform(digest, block, transforms);
            for(size_t i = 0; i < BLOCK_INTS - 2; i++)
            {
                block[i] = 0;
            }
        }

        /* Append total_bits, split this uint64_t into two uint32_t */
        block[BLOCK_INTS - 1] = total_bits;
        block[BLOCK_INTS - 2] = (total_bits >> 32);
        transform(digest, block, transforms);
    }
}